Similar problem getting off rear coupler. My problem is a bit different. Can't get the nut loose. I've got the rear differential and shaft out. But for the life of me I can't get the 19mm nut to break loose so I can get the coupler off. Tried breaker bar, 1/2 impact. Thought it might be reverse thread. Tried that too. No joy. Any help getting the nut off would be greatly appreciated, Ross